This invention relates to an automatic telephone response system and, more particularly, to a telephone inquiry voice response system in which responses are supplied in real time to one ore more inquiring telephone lines or stations.
Numerous inquiry-response systems are known in the art. Typically, they include a storage device at a central location having predetermined response messages stored therein to be transmitted to requesting remote stations or the like. To this end, computers including a mass storage device for storing messages or segments thereof, either in analog or digital form, are employed to respond to inquiries via telephone lines or the like from any of now numerous terminal equipments, for example, telephone station sets, multifrequency signaling units, teletypewriters, et cetera. In prior known systems, the computer is programmed to recognize that an inquiry has been made, determined an appropriate response, concatenate the response from the stored information and transfer the desired information from the mass storage device to the requesting line and, hence, the requesting station or terminal equipment. In some known systems, digital words representing segments of speech are transferred from the mass storage device to an output buffer and then to the requesting lines. Additionally, some systems are arranged to handle requests from a plurality of lines simultaneously. This is achieved by employing input and output multiplexers. In general, the output multiplexers have included buffer storage stages for temporarily storing the analog or digital signals which make up the desired response message to be outputted. For the most part, these prior known systems have employed complex and expensive arrangements for obtaining the desired speech output. Thus, although they may be satisfactory for some applications, they are unattractive for others from a commercial standpoint.
More recently, output multiplexers of the socalled direct memory access type have been advantageously employed to supply response messages in substantially real time to a plurality of requesting telephone lines. One such multiplexer arrangement is disclosed in U.S. Pat. No. 3,990,050 issued to N. J. Kolettis, K. C. O'Brien and G. J. Owens, on Nov. 2, 1976. In this prior direct memory access multiplexer digital words to be outputted are supplied to dedicated buffers, i.e., word locations, in storage stages serially arranged in a single storage unit of a random access memory (RAM) associated with a central processor. The words to be outputted from the buffers in the RAM storage stages are read one at a time in a prescribed sequence of read intervals to corresponding output lines. Since the storages stages are serially aligned in this prior system, expansion to accommodate the addition of lines would require extensive redesign to realize proper timing intervals and the like. Such redesign and resultant rewiring are extremely undesirable. Thus, although the prior direct memory access voice response system may be advantageously employed for applications which do not require substantial growth, it is undesirable for use in systems where rapid and substantial addition of new lines is anticipated.